Hello mellinger,
You can put something under the object (on the turntable) that has irregular texture pattern with distinguishable features - could be just some printed pattern or a textile, jeans, etc.
just make sure that this pattern is moving with the object. Also, depending on the object that you are working on and the turntable size, may be reasonable to leave some blank (untextured) space under the object in between with the artificial textured background - it would help to avoid excessive manual work while removing the background parts from the model or during masking.